Mika releases Yu, and they witness some of Guren's human experimentation as they pass by. Mika refuses to trust Guren but agrees to do what he can to save his family.
Guren reveals that Saitō is actually a second progenitor. He then takes Yu and Mika to see the sixth trumpeter, the seraph imprisoned within a barrier of Guren's home. This seraph continuously summoned horsemen into their world over the past eight years.
Mika chats with Yu and releases him from the container. Yu's horn and wing retract into his body afterward. Mika tells Yu that everyone else is asleep. They are in the building where Guren was involved with human experimentation at his residence in Aichi Prefecture. Yu insists that Guren is not that bad of a guy, and Mika asks if the guy experimenting on his family is "nice."
Yu peaks in a room to see other beings trapped within containers like he was.
Even so, Yu insists Guren has good reasons for human experimentation. Yu and Mika continue to argue. Mika says that Guren's demon is controlling him, but Yu says his demon controls him, too. They chat more, and Yu says he will do anything to get his family back. Yu says the ends justify the means. He regrets never telling Akane that they were family. He says being human means doing whatever it takes to protect his friends and family. Mika hesitates before agreeing, and they shake hands.
Guren approaches the pair. He admits to taking over most of those experiments after the catastrophe. Yu asks him who he took them over from, but Guren does not answer.
Guren takes them to an elaborate glowing barrier and says it is sealing a monster inside. Both the Emperor's Demons and the Hyakuya Sect joined forces to build this barrier, and it still barely keeps the creatures contained. Guren explains that the Emperor's Moon and the Hyakuya Sect were rivals until the catastrophe, and then the Emperor's Moon formed the basis of the Demon Army. Guren explains that the Hyakuya Sect must have experimented on both Yu and Mika. Yu says his memories were erased, but he was in a cell before he went to the orphanage. He vaguely recalls meeting with Mahiru but does not remember her identity.
Mika asks how long Guren has been pulling their strings. Guren denies it, but he says Saitō is most likely behind everything. He reveals that Saitō is actually a second progenitor. Mika recalls being spoiled by Saitō in his childhood.
Mika asks Guren who he is, what experiments he is running, and how long he has been planning this. Guren says he was not much of anyone before, but he plans to be at the forefront of the whole world this time. Guren reveals the sixth trumpeter is within the barrier and enters it.
Mika advises Yu against following Guren due to the danger, but Yu says they won't know anything if they don't follow him. When Mika says he will go first, Yu insists on them going together. They enter the barrier.
A four-winged seraph screams as blood pours down his face. He is in the air with a large trumpet, but chains connect him to the ground.
Four the past eight years, this seraph has continually summoned the horsemen into the world to punish humanity for its sins.
Yu first asks what this creature is and then asks about himself instead.
List of characters in order of appearance:
Manga panels provide a visual overview of the events of Chapter 63 with depictions of the characters, Seraph of the End world and scenarios.